JPH04256759A - Apparatus for expanding constricted part of internal tube - Google Patents

Abstract

PURPOSE: To provide a device capable of surely expanding the constriction section of a body internal tube in a short time with no problem. CONSTITUTION: This device is provided with a portion made of a shape memory alloy and having a cylindrical outside contour, the portion maintains the cylindrical outside contour at the migration temperature higher than the ambient temperature and lower than the body temperature to be expanded in the radial direction, and the diameter at the temperature lower than the migration temperature is selected smaller than the diameter of a body internal tube.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to devices for dilating strictures in arteries, ureters, bile ducts, or similar body ducts.

0002

BACKGROUND OF THE INVENTION Occlusions in blood vessels, such as arteries, are usually dilated by first removing deposited material, such as plaque, by, for example, cutting, aspiration, or similar procedures. However, this cannot be done on tissue material due to the risk of damage. If the stenosis is not completely occluded and only a stenosis or stenosis has formed, or if the stenosis was initially completely occluded but a certain degree of circulation has been achieved using the method described above, the stenosis should be removed in the radial direction. It is hoped that this will be expanded. Such dilation occurs not only in blood vessels, but also in other body vessels, such as the ureters, bile ducts, or the like.

Conventionally, so-called balloon catheters have been used for this purpose. The balloon catheter has a dual inner diameter that provides instantaneous radial expansion. This inner diameter remains if the balloon catheter is removed again. Long-term dilation of such strictures is also already known. For example, an expansion section can be fixed axially on such a balloon catheter, introduced together with the catheter, and plastically deformed by expansion of the balloon catheter, increasing the radial dimension of the expansion section so that the expansion section can be attached to the wall of the stenosis. It is known to remove the balloon catheter after pushing it in and blowing out the air from the balloon catheter, while leaving the dilation in place in a plastically deformed state. Such a part is provided with an extension in the form of a helical sleeve.

An important disadvantage of the last mentioned method is that the sleeve is placed around the catheter and introduced into the stenosis. Firstly, axial fixation is expensive and cannot be achieved reliably, either the sleeve remains when pushing the catheter forward, or it is difficult to later dissociate the sleeve from the catheter. Furthermore, the extensions located on the outer periphery of the balloon catheter are at great risk of being damaged. Moreover, in the case of such dilations with a balloon catheter, the radial expansion is first carried out beyond the final desired radial dimension to be achieved. This is because such dilations, as long as conventional biocompatible materials have sufficient hardness to hold the stenosis open, can undergo significant deformation before permanent plastic deformation with the desired radius occurs. This is because it has an elastic deformation range. This applies in particular to helically shaped extensions, as already mentioned.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for dilating a stenotic region that avoids the above-mentioned drawbacks and enables simple, problem-free and reliable dilation of a stenotic region in a short period of time. The goal is to provide the following.

[0006]

[Means for explaining the problem] The problem is to provide a device for dilating a stricture in a body duct, such as an artery, ureter, bile duct, or the like, from a shape memory alloy with a cylindrical outer circumferential surface. and is adapted to expand radially while maintaining a cylindrical profile at a transition temperature above ambient temperature but below body temperature; At low temperatures, the solution is that the diameter is less than or equal to the diameter of the internal tube.

[0007] The present invention provides an extension made of a shape memory alloy, which at a temperature above a predetermined transition temperature below body temperature,
In other words, they have proposed a shape that corresponds to the desired expansion of the internal canal at body temperature. In this case, in a preferred embodiment the shape memory alloy is a nickel titanium alloy. Furthermore, Cu-
Zn-Al or Cu-Al-Ni alloys can also be used. Such alloys include Nitinol, Biome
It is known as Tall (Toki Co., Japan) or Memotal.

[0008] The martensitic reaction or transformation which results in a shape change is carried out by a temperature change. Whereas the transition temperature can in principle lie within a wide range below body temperature, in one embodiment of the invention the transition temperature is 2.
It is 0°C. This temperature is sufficiently low compared to the temperature at which the shape memory alloy section reliably expands at high temperatures. At the same time, said temperature is such that the part taken by the practitioner at ambient temperature, i.e. the part with a small diameter at a low temperature, radially after a predetermined time sufficient to introduce said part into the body and into the stenosis. has been chosen to expand.

[0009]

EMBODIMENTS The present invention can be implemented in various embodiments. For example, the part made of a shape memory alloy may consist of a curved flat metal sheet, or the part may consist of a wire.

In the first case, according to one embodiment of the invention, the sheet metal part has a spiral shape at a temperature below the transition temperature and expands into a cylindrical wall when transitioning above the transition temperature. Such an arrangement has the advantage that no axial shortening of the extension occurs. Such a shortening is achieved by forming a cylindrical wall in which the shape memory alloy is provided with a longitudinal slit and a web region remaining between the longitudinal slits, in which adjacent longitudinal slits oriented parallel to each other are offset relative to each other in the longitudinal direction. occurs in an advantageous embodiment characterized in that said portion maintains a diamond-shaped intermediate chamber between the webs and expands radially when the temperature increases above the transition temperature. This configuration is relatively simple to fabricate. That is, a metal sheet of the desired dimensions is punched out as a metal lath, then bent into a cylindrical shape and the longitudinal edges parallel to the slits are welded together. The shortening of the part upon radial expansion is taken into account by the larger predetermined length.

[0011] In this case, the part made of a shape memory alloy is made of a metal wire mesh or a metal knitted body and is configured as a cylindrical wall, or the part made of a shape memory alloy is made of a wire guided in multiple spirals. This also applies to the embodiments described above.

A very advantageous embodiment of the invention is characterized in that the metal material is constructed in the axial direction in the form of a meander, the individual meander being bent approximately in the form of a ring. If the meander has an axial bend, in accordance with an advantageous embodiment of the invention, the bend of one meander leg is connected to an adjacent meander leg. Advantageously, this connection is made by soldering. According to another embodiment of the invention, if all the bends are not connected in a typical manner with the adjacent meander legs, i.e. only some of the meander legs are connected, then according to another embodiment of the invention, the connection The bonding force is configured to be larger than the bending force of the meander bending portion. Thereby, the device according to the invention, also called an implant or a stent, can be stretched or upset in the axial direction to the extent that the meandering parts are not fixedly connected to each other by a joint, e.g. by soldering, and are located elsewhere. The length can be adjusted without tearing or breaking the joint (solder joint).

[0013] On the other hand, the joining point is designed as a defined breaking point, so that when an implant constructed in the above-mentioned manner is subsequently removed again, the joining occurs if one end of the wire forming the implant is pulled. The point must be broken, the wire must be stretched, and the implant must be easily removed. Furthermore, not only in implants constructed in the above-mentioned manner, but also in implants constructed in a circular weft or spiral configuration, at least one end of the wire forming the device is formed with a ball. It is advantageous to have one. In this case, the bulb is engaged by grooved forceps and stretching of the implant is achieved. In an advantageous embodiment of the invention, the device has a connecting web extending approximately parallel to the axis, from which laterally ring-shaped extensions extend. In this case, the extensions extend from both sides of the connecting web and are arranged staggered in the axial direction. Alternatively, in such an implant the appendage extends at an angle of 90° to the connecting web or the appendage extends at an angle different from 90°, advantageously between 50° and 70°. It can extend at an angle of .

The external contour of the implant is usually cylindrical, whereas, depending on the particular application, a double-cone external contour is provided in a particularly advantageous embodiment.

In an advantageous embodiment of the invention, the metal part of the implant described so far is embedded in tissue-compatible plastic or silicone, despite the fact that there is an intermediate chamber in the area between the memory alloys. A closed peripheral wall is obtained. This prevents cells from growing inside the implant in the case of malignant tumors.

The implant of the present invention can be used in a variety of locations for a variety of purposes. It is therefore used in the urethra, ureters, bladder neck, bile ducts, blood vessels such as arteries and veins, esophagus, trachea, intestines, especially rectum.

The present invention provides a strong, highly flexible, axially curved implant of the type having a meandering guided wire.

Further advantages and features of the invention are explained in more detail in the subclaims and in the following description of an exemplary embodiment of the invention with the help of the drawings.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a device according to the invention (hereinafter referred to as a stent) for dilating a stricture in a body duct, such as an artery, ureter, bile duct, or the like. The stent of FIG. 1 has a spiral shape in the cold state and assumes a generally cylindrical wall shape upon transition over the transition temperature to the hot state. The stent according to the invention is made of metals with shape memory function, in particular nickel-titanium alloys, Cu-Zn-Al,
Alternatively, it is made of Cu-Al-Ni. Shape memory alloys are known by the names Nitinol, Bimetal, or Memotar. The manufacture of the stent of FIG. 1 is carried out by bending the stent into a hot shape, ie into the cylindrical wall shape of FIG. 1, and then heat treating. After cooling below the transition temperature, the stent is brought into a permanently coiled cold configuration. When the stent is rewarmed beyond the transition temperature, which is in the range 30 to 35°C, advantageously 35°C, the stent assumes a cylindrical-walled hot shape;
Take this hot shape again.

FIG. 2 shows another stent in the form of metal lath. In this case, a number of slits are punched out in a piece of sheet metal in the same row, one behind the other and one after the other, the adjacent slits being longitudinally offset from each other, and the upper and lower sides of one slit being Both regions overlap the end region of the slit located laterally. When the sheet metal piece is stretched and expanded transversely to the longitudinal direction of the slit, the slit is enlarged into a diamond shape. Such sheet metal pieces are designed in the form of cylindrical walls and are connected to one another at their longitudinal edges parallel to the slits, for example by welding or brazing. The sheet metal pieces are brought to an enlarged shape exhibiting a rhombus, as shown on the right side of FIG.
(left side in Figure 2). This stent also recalls a hot shape that expanded upon warming over the transition temperature. Upon radial expansion, the stent of Figure 2 (Figures 3 and 4)
The stent in FIG. 1 is also shorter than the stent in FIG. This shortening is taken into account by appropriate selection of the length. The width of the stent is significantly smaller, advantageously approximately 0.2 mm
in range.

FIG. 3 shows a stent made of metal knitting or metal weft knitting, which likewise has a cylindrical wall-like outer contour. Temperature and shape treatments are again carried out in the manner previously described, so that the stent is expanded from a small diameter elongated state to a radially expanded hot shape upon increasing the temperature above the transition temperature. The same applies to helical and coiled configurations of stents made of metal wires with shape memory functionality, provided that suitable heat treatments are also carried out in this case.

FIG. 5 shows the weave structure of a circularly knitted implant according to the invention. The implant has a regular weave of weft threads 11, the weave of the legs 12 having a head 13 of the upper attachment point and a wrapped foot 14 of the head of the lower attachment point. .

In an advantageous embodiment, a ball 16 is attached to the end of the weft thread 11. If you wish to remove the attached implant again for some reason, use grooved forceps to remove bulb 1.
6 is grasped and pulled, thereby pulling the implant's mesh structure and removing it from the body cavity in which it was installed.

The aforementioned removal by elongation of the weft threads forming the respective implant is also possible in the configuration of FIGS. 6 and 7. This implant consists of a wire wound in a meander shape in the longitudinal direction (therefore, the meander itself extends transversely to the longitudinal direction).
In this case, the meandering section is bent into a ring shape, so that the mutually opposite webs of adjacent meandering sections are bent together. Such implants are
It has the significant advantage of being able to vary in length without significantly affecting the cross section. The implant is swaged or extended to its normal length and is held in the occupied position by friction between the implant and the surrounding body vessel wall.

In an advantageous embodiment, the leg 19 of the meander 20
has a bend 21 which reaches an adjacent meander leg, for example 19'. At least a portion of the bent portion is connected to the adjacent meander leg portion 19.
' and may be connected by a soldering point 22. Depending on the intended use, all bends can be connected to adjacent meander legs, which limits the length of the implant. In addition, only parts of the bends may be connected, some of the bends being not provided with soldering points, so that the length can be varied within a certain range. Furthermore, the implant can be constructed without any bends being rigidly connected to the adjacent meander legs, with the bends allowing radial or angular flexural deformation of the implant.

The implant of FIGS. 6 and 7 also has a ball 16 at the wire end, so that the implant can be removed by elongation of the wire forming the implant. If a brazing point 22 is provided, the fixing force at the brazing point is significantly smaller than the tearing force of the wire;
It is desired that the deflection force be greater than that of the wire rod in the range of 18.

Another implant according to the invention is also shown in FIG.
It may have the aforementioned cylindrical outer contour, as shown in FIG. 7, but it may also have a conical or double-conical shape, as shown in FIG. diameter is increasing.

The implant according to the invention of FIGS. 6 and 7 has a significantly higher flexibility than that of the configuration of FIG. The implant of Figures 6 and 7 is substantially fully bendable. The metal implant according to the invention may be embedded in a compatible plastic or advantageously silicone, the plastic or silicone having the same contour as the stent. This prevents malignant tumors in the area of the implant from metastasizing through the stent.

Stents formed with meandering structures may be installed in a variety of ways and for a variety of purposes. Particularly advantageously, such a stent is installed as a ureteral stent in the prostatic range in order to extend the ureteral range in the largest case of the ureteric prostate. The stent is particularly well adapted to the male ureter due to the flexibility of its double-linked structure. The stent can vary in length so that the posterior or lateral end of the stent does not reach the extent of the external sphincter, so that the function of the stent is not compromised. Particularly for such uses, the aforementioned possibility of withdrawal of the stent by stretching and pulling out the wire forming the stent is advantageously exploited.

A further advantageous construction of the implant according to the invention is shown in FIG. 8, and FIG. 9 shows an exploded view. Such stents are called skeletal stents. The stent has spines or connecting webs 31 extending substantially parallel to the axis.
, at an angle perpendicular to the bonding web (Figure 8
) or from both sides at an angle different from the right angle, advantageously in the range between 50° and 70°.
is extending. Additional parts (ribs) 3 extending towards each side
2, 33 are in the exemplary embodiment alternately offset from each other in the longitudinal direction of the spine or connecting web 31, so that the ring-shaped extensions 33 extending on one side are located between the extensions 32 extending on the other side. They are respectively engaged within the space.

[0031] The additional part 32 in the low temperature state and the high temperature state,
The length of 33 and the diameter of the implant are such that in cold conditions there is an overlap of the peripheral walls of the implant, otherwise the extensions 32, 33 extend from either side of the connecting web 31.
is chosen so that it occupies the same height as the height of the connecting web 31. The implant shown in FIGS. 8 and 9 also has high flexibility and longitudinal deflection deformability. Furthermore, the extensions 32, 33 are arranged in close contact with each other such that fluid from the surrounding tissue retained by the implant in the hollow chamber can flow into and out of the implant, but does not allow tissue to enter the interior and cause stenosis. It is located. The configuration of FIG. 9 provides somewhat greater stiffness than the configuration of FIG.

FIG. 10 shows another implant material. In this case, long holes are punched out in the thin plate, and adjacent long holes are arranged alternately offset from each other.
Therefore, elongated holes of short length are also formed in the end region.

[Brief explanation of the drawing]

1 shows a first embodiment of the device according to the invention for dilating a stenosis in a body vessel in a spiral starting position; FIG.

FIG. 2 shows a further embodiment of the device according to the invention with axis-parallel slits in the form of metal laths;

3 shows a further embodiment of the device according to the invention in the form of a wire mesh; FIG.

FIG. 4 shows a further embodiment of the device according to the invention in the form of a helically wound wire;

FIG. 5 shows a stitch pattern in a further embodiment of the device of the invention in the form of a stent with circular weft knitting.

FIG. 6 shows a further embodiment of the device of the invention in the form of a stent with meander-shaped wires, each meander being bent into a partial ring and having a cylindrical outer contour; Schematic illustration of an example.

7 is a schematic representation of a further embodiment of the device of the invention in the form of an implant, similar to FIG. 6, with a double cone-shaped outer contour; FIG.

FIG. 8 shows a further embodiment of the device of the invention in the form of an implant.

9 shows another variation of the implant of FIG. 8 in a deployed starting position; FIG.

FIG. 10 is a plan view of a pre-stamped sheet metal for constructing a further embodiment of the device of the invention in the form of an implant;

[Explanation of symbols]

Claims (25)

[Claims] 1. A device for dilating a stenotic site in a body duct, such as an artery, ureter, bile duct, or the like, the device comprising a portion of a shape memory alloy having a substantially cylindrical outer contour. and wherein the portion is radially expanded while maintaining a cylindrical outer contour at a transition temperature above ambient temperature and below body temperature, and wherein the portion is made of the shape memory alloy. 1. A device for dilating a constricted region of a body canal, characterized in that its diameter at low temperatures is smaller than the diameter of the body canal. 2. Device according to claim 1, characterized in that the shape memory alloy is a nickel-titanium alloy. 3. Device according to claim 1, characterized in that the transition temperature is between 30° and 35°C. 4. Device according to claim 1, characterized in that the transition temperature is 35°C. 5. Device according to claim 1, characterized in that the part made of shape memory alloy is a bent flat sheet metal part. 6. Device according to claim 5, characterized in that the sheet metal part is spiral-shaped below the transition temperature and expands into a cylindrical body above the transition temperature. 7. The part made of a shape memory alloy is a cylindrical body having longitudinal slits and a web region formed between the longitudinal slits, and adjacent longitudinal slits extending parallel to each other. are offset from each other in their direction of extension, and said portions expand radially when the temperature rises above ambient temperature, forming diamond-shaped openings between the webs. Item 5
The device described. 8. Device according to claim 1, characterized in that the part made of shape memory alloy is a part made of wire. 9. Device according to claim 8, characterized in that the part made of the shape memory alloy is formed as a tube made of a metal mesh or a flat knit. 10. The device according to claim 9, characterized in that the weft knitted fabric is a circular weft knitted fabric. 11. The portion made of the shape memory alloy is formed from a spirally wound wire,
9. The device according to claim 8. 12. The metal material as a wire rod or a flat material is formed in the form of a meander in the axial direction, and the individual meander (20) is bent approximately in the form of a ring. 9. The device according to any one of 1 to 8. 13. Claim 1, characterized in that the meander (20) has an axially bent portion (21).
2. The device according to 2. Claim 14: The bent portion of the meander leg (19) (
21) is connected to the adjacent meander leg (19) and the connecting part (2
14. Device according to claim 13, characterized in that it forms 2). 15. Device according to claim 14, characterized in that the bonding force of the coupling part (22) is greater than the bending force of the meandering part (17, 18). 16. Claim 14, characterized in that the tensile strength of the joint (22) is lower than the tensile strength of the wire itself.
or the device according to 15. 17. Device according to claim 9, characterized in that a ball (16) is formed at at least one end of the wire forming the device. 18. The device has a connecting web (31) extending approximately parallel to its axis, from which laterally extending ring-shaped extensions (32, 33) extend. Device according to one of claims 1 to 5 or according to claim 8, characterized in that: 19. Device according to claim 18, characterized in that the extensions (32, 33) extend from the connecting web (31) on both sides and are each offset alternately in the axial direction. 20. Device according to claim 18, characterized in that the extensions (32, 33) extend at an angle of 90° to the connecting web (31). 21. The extensions (32, 33) are at an angle to the connecting web (31), preferably between 50° and 70°.
20. Device according to claim 18 or 19, characterized in that it extends at an angle of . 22. Device according to claim 1, characterized in that it has a cylindrical outer contour. 23. Device according to claim 1, characterized in that it has a conical outer contour. 24. Device according to claim 1, characterized in that it has a double cone-shaped outer contour. 25. Claims 1 to 2, characterized in that the metal element of the device is embedded in a closed peripheral wall made of a tissue-compatible basic material, in particular silicone.
4. The device according to any one of items 4 to 4.